Effectiveness of eucalypt plantations as a surrogate habitat for birds

In the fragmented forest landscape of Europe, tree plantations comprise an increasingly important fraction of the matrix surrounding natural forest fragments. Plantations may provide habitat for forest biodiversity, which may enhance landscape connectivity and regional biodiversity. I compared the diversity and composition of bird communities in eucalypt plantations of three ages (young, intermediate and mature) and with low management intensity with respect to pine plantations, native forests and shrublands. Differences in composition of species and species groups were analyzed with PERMANOVA and visually represented using NMDS ordinations. Species groups were established according to diet, habitat and microhabitat preferences, and conservation status. A total of 887 bird encounters and 45 species were recorded. Native forests had the highest species richness per site and per sample, followed by pine plantations and shrublands. Eucalypt plantations had the lowest species richness, and decreasing with age, and the lowest bird abundance. According to composition, two habitat groups could be distinguished: wooded habitats, including native forests and plantations except young eucalypt plantations; and shrubby habitats, with shrublands and young eucalypt plantations. Native forests and pine plantations had the most similar composition among wooded habitats, and were associated with forest specialists, whereas species having unfavorable conservation status were associated with shrublands and young eucalypt plantations. In eucalypt plantations, birds were mainly associated with shrubs at young ages and with canopies at older ages, with flowers as an important food resource. The paucity of birds in eucalypt plantations contrasted with the diverse and abundant avifauna in pine plantations. The alien status and taxonomic isolation of Eucalyptus globulus in the region, together with specific features of its leaves and bark, may explain the low suitability of eucalypt plantations, by limiting the presence of phytophagous insects and thus the availability of prey for birds.